Method for controlling position of a plurality of machining shafts each including a machine tool fitted thereto

A method of controlling the position of a plurality of machine shafts for a wood working machine, each shaft including a machine tool fitted thereto and supported by a movable block engaged with a screw threaded rotary shaft driven by a servomotor, said movable block being movable in the axial direction of the screw threaded shaft when the screw threaded shaft is rotated to thereby control the position of the machine shaft supported by the movable block, the method controlling movement of the machine shaft for a predetermined distance and comprising:

• a first step of rotating said screw threaded rotary shaft at a first rotation speed so that the movable block is moved in a first direction through a first distance which is larger than backlash between said screw threaded rotary shaft and said movable block;
• a second step of rotating said screw threaded rotary shaft at a second rotation speed so as to move said machine shaft through said predetermined distance to an intermediate position spaced apart from a final position of said machine shaft by a distance equal to said first distance;
• and
• a third step of rotating said screw threaded rotary shaft at a third rotation speed so as to move said movable block along said screw threaded shaft to a low speed in a direction opposite said first direction and for a distance equal to said first distance to thereby position the machine shaft in its final position, said third rotation speed being lower than the second rotation speed of said screw threaded shaft and being sufficient to prevent occurrence of overshoot of said movable block beyond said screw threaded shaft.